Enteric Nervous System

The enteric nervous system (ENS) is a complex network of neurons and glia, reminiscent of the central nervous system (CNS), innervating the gut and controlling intestinal function.

The occurrence of enteric pathology in dementia is well recognised.

Gastro-intestinal dysfunction, particularly constipation (a clinical expression of enteric neurodegeneration), is a prevalent symptom in neurologic and systemic diseases associated with neurodegeneration. This dysfunction is partly related to abnormalities and cell loss in the ENS.

Additionally, during aging there is evidence of a loss of excitatory (cholinergic) enteric neurons and interstitial cells of Cajal whereas inhibitory neurons appear unaffected.

A cholinergic hypothesis of neuronal vulnerability in the CNS is thought to contribute to the cognitive decline seen in aging and neurodegenerative disease.

Beta amyloid (AB) peptides and it's precursors are well described in the peripheral nervous system including the ENS.

Recently, a transgenic AD mouse model confirmed the presence of AB in the small and large intestine during aging.

The ENS may provide a valuable entity to study the pathophysiology of neurodegeneration as well as present as a pathological marker during early stages of AD.